Kkula
Browse Questions » SIMATIC S7-400 / S7-400H / S7-400F /FH: Central processing unit 416 Led Condition Display Issue

About User

Siemens Self Support

Questions Asked: 37.9K

Answers Given: 32

Statistics

Tags

0
  • Open
Siemens Self Support
Asked:18 Oct 2025

SIMATIC S7-400 / S7-400H / S7-400F /FH: Central processing unit 416 Led Condition Display Issue

Dear expert,
As per your privious susggetion i am using sfc 51 for LED Status dispaly of PLC s7-416-2Dp. But while i have downloaded it i am not getting proper status of INTF(1 LED) EXTF (2 LED) on cpu while observing online with step 7 manager. Please Conform me what could be problem?
also whenever plc goes in stop mode i am not able to obser it in s7 manager did thisstatus indication will work on SCADA afterwords?
Thanks
prashantb

#sosflex #SIMATIC S7-400 / S7-400H / S7-400F /FH #siemens
1Answers 4Views 0Votes
0 Likes 0 Favourites 0 Followers 0 Comments
Answers(1)
Siemens Test Added an Answer on18 Oct 2025

LED Status Display & Stop Mode Observation - S7-416-2DP

Dear Prashantb,

Regarding the SFC 51 implementation for LED status display on your S7-416-2DP PLC, discrepancies between the actual LED status and the online view in STEP 7 Manager can arise due to several reasons:

  • Hardware Configuration Mismatch: Verify the hardware configuration in STEP 7 precisely matches your PLC setup. Specifically, check the module addresses and parameter settings for the CPU.
  • SFC 51 Configuration: Ensure SFC 51 is correctly configured to read the INTF (1 LED) and EXTF (2 LED) status bits from the PLC diagnostics memory. Double-check the assigned memory locations within the SFC 51 block.
  • Cycle Time: A very short cycle time for SFC 51 might cause missed updates. Consider increasing it slightly.

Stop Mode Observation: The status indication in STEP 7 Manager during STOP mode is often limited. While SFC 51 should reflect the stop state eventually, it may not be immediate. SCADA systems generally read PLC status via communication protocols (e.g., Modbus, Profibus). Once communication is re-established after the PLC returns to RUN mode, the SCADA system should reflect the correct status, assuming your SCADA program is correctly configured to read those PLC tags.

For detailed troubleshooting and configuration guidance, please refer to the following resources on SiePortal:

If you continue to experience issues, please provide your STEP 7 project (or a relevant section) for further analysis.

Sincerely,
Siemens Self Support

0